1. Field of the Invention
This invention relates to the recovery of nickel from aqueous commercial solutions containing nickel values by extraction of the nickel value therefrom with an organic solution containing an oxime extractant and an equilibrium modifier followed by stripping of the nickel values from the organic solution by a concentrated aqueous ammoniacal solution from which the nickels can then be recovered. The use of the equilibrium modifier and the concentrated ammonia stripping solution provides advantages in that (1) there is an increase in the nickel transfer of the reagent, (2) the strip solution can be built to a higher nickel concentration giving a lower volume nickel containing solution for further processing and (3) a lesser number of stripping stages are required.
2. Statement of Related Art
U.S. Pat. Nos. 4,065,502 and 4,157,012 describe a group of .beta.-diketones which are useful for recovering nickel or copper values from aqueous ammoniacal leach solutions, U.S. Pat. No. 4,152,396 describes the recovery of nickel or cobalt using fluorinated .beta.-diketones from acidic aqueous solution.
U.S. Pat. Nos. 4,148,813 and 4,148,816 describe the solvent extraction of cobalt and nickel employing mercaptide extractants. A description of a commercial operation recovering nickel values can be found in the The S.E.C. Nickel Process, Hydrometallurgy, CIM Bulletin, February 1974, pp. 82-86. Reference is made to LIX.RTM. 64N, a benzophenone oxime extractant reagent. Reference to this process is also found in a reprint from the Engineering and Mining Journal, 1972, entitled "New Recovery Process Can Yield Both Electrolytic Nickel and Copper". The flow sheet shown therein is also found in a paper presented in a Symposium on Solvent Ion Exchange, American Institute of Chemical Engineers, Arizona Section, Tuscon, 1973, by R. D. Eliassen, Manager, Chemical Division of S.E.C. Corporation, entitled "The Operation of a Nickel Solvent Extraction and Electrowinning Circuit", pp. 1-7.
The use of an acetophenone oxime extractant in the recovery of copper and nickel from ammoniacal solution is described in International Symposium on Copper Extraction and Refining, Feb. 22-26, 1976, Las Vegas, Nev., Volume II, Extractive Metallurgy of Copper, Hydrometallurgy and Electrowinning, Chapter 54, pp. 1039-1055, entitled "Shell Metal Extractant 529--A New Selective Extractant for Copper and Nickel", by A. J. Van der Zeeuw.
Copper and nickel extraction in ammonia systems are also described in "The Use of pH Control In Solvent Extraction Circuits", at pp. 6-9 and FIGS. 9-12, of a paper distributed by Henkel Corporation, which paper was presented at the AIME Annual Meeting, New Orleans, La., Feb. 19-23, 1979.
The use of alkylphenols in combination with oxime extractants is described in CIM Special Volume 21, ISEC, 1977, pp. 40-48, in an article "The Effect of Alkyl Phenols on the Copper Transfer Properties of the Extractant Acorga P-1" by R. F. Dalton. U.S. Pat. No. 4,336,231 which is a continuation of U.S. Pat. No. 4,231,888, a division of U.S. Pat. No. 4,142,952, and which describes copper extraction with either salicylaldoximes or benzophenone oxime and alkyl phenols. Nickel is found in a general list of metals.
The use of equilibrium modifiers in the extraction of copper is also discussed in "Modified Aldoxime Reagents for the Solvent Extraction of Copper" by R. F. Dalton and G. W. Seward, pp. 107-116, in Reagents in the Minerals Industry, Edited by M. J. Jones and R. Oblett, Institute of Mining and Metallurgy, September 1984.
U.S. Pat. No. 4,507,268 describes equilibrium modifiers such as tridecanol, nonylphenol and tributyl phosphate employed with various hydroxyaryl ketoximes and hydroxyaryl aldoximes.